The newest version of OS X is now out for just $19.99 exclusively through the Mac App Store, and for an additional $19.99 users can even upgrade over to OS X Server. So what sets the new version apart from OS X 10.7? The new OS X 10.8 “Mountain Lion” features plenty of new enhancements for the Mac such as iMessage support, a Notification Center, Power Nap updating during sleep mode, Dictation, sharing tools, Game Center, Gatekeeper for improved security and better iCloud integration.
The newest version of OSX adds many features that help bring it closer to the feel of the iPad and iPhone’s popular iOS, while still maintaining the overall OSX look and feel. Not surprisingly, the Mac App Store exclusivity of this upgrade means that many users are attempting to download this at once, and this results in only some of the users actually getting it to work thanks to server stress. Knowing Apple, they will do what they can to open up new servers and help make the download process as smooth as possible but even if it does prove to be a small hassle to download, at just $19.99 and with so many great iOS-like features heading its way- it is worth the wait.[ source ]